Water absorption and retention in the soil profile is a significant issue for those involved in the agricultural industry. Different soil types have varying water retention and absorption characteristics. In sandy soils water is usually able to easily penetrate the soil profile. However, the water quickly passes through the soil profile and out of the root zone of most agricultural plants. In irrigated areas this means that the frequency of irrigation must be increased. By contrast, clay soils have low water absorption rates but have significantly higher water retention. Low absorption rates in clay soils result in increased run-off which can intensify erosion. Other factors, such as hydrophobic or non-wetting soil properties also influence water behaviour. These soil characteristics can adversely affect the productivity of all types of plants used in agriculture including crops, pasture, trees and vines.
Various methods have been used to improve water absorption and water retention in soil profiles. Gypsum (Calcium Sulphate) is used to improve soil structure and increase water absorption. One of the main rationales for using gypsum is to reduce surface sealing and improve infiltration. The use of gypsum, however, leads to an increase in salinity which can threaten plant performance especially in soils with already high concentrations of salt, such as those soils found in Australia.
Surfactant or wetting agents are applied to plant growing media, such as soil, to improve water penetration and rewetting properties of the growing media. Hydrophilic surfactants prevent rapid drainage and improve water retention. Surfactants are also able to break down the hydrophobic build up around sand and soil particles, such as those found in non-wetting sands. However, surfactants may be affected by salts and other compounds found in the media. Furthermore, they may not be suitable for prolonged use when growing edible crops because of potential negative health effects. Tests have suggested that certain surfactants are acutely toxic to animals. Therefore, because of the potential risks the use of surfactants is cautioned, especially near sensitive environments such as waterways.
The application of chemicals to improve soil characteristics is undertaken in various ways. The chemicals, in a granular or powder form, can be simply spread across the soil surface or added during ploughing to minimise the loss due to run-off. In irrigated areas the chemicals are often sprinkled on the ground at an inlet prior to flood or furrow irrigation. Alternatively, a concentrated liquid emulsion can be added to a water body used as a source for irrigation water. However, these methods are quite imprecise which results in more chemicals being added to the agricultural environment than are actually necessary. This excessive use results in run-off and leached water from agricultural land having high concentration of chemicals which can adversely affect surrounding ecosystems.
The loss of water through evaporation and water infiltrating the ground prior to, or during, flood and trench irrigation means that these forms of irrigation are inefficient when used on vines and fruit trees. For these reasons various types of irrigations systems, such as drippers and micro-sprays, are used to increase the efficient use of water. However, the problem with these types of systems is that the granular preparations and emulsions cause blockages and therefore are not suitable for transporting the chemicals.
It is therefore an object of the present invention to provide a water additive that can be used in the agriculture, viticulture and horticulture industries that reduces the amount of water required when growing agricultural crops, trees and vines.
It is a further object of the present invention to provide a biodegradable water retention polymeric concentrate which is able to be transported through drip and spray irrigation systems including irrigation systems such as overhead centre pivot booms.